An Egyptian civilian has been killed and a police officer injured in a drive - by shooting in the capital Cairo.The shooting took place on Friday morning in Cairo's Al-Marg district after armed men in a vehicle, accompanied by a pickup truck, attacked a security checkpoint and killed the 23-year-old man and injured the police officer. Reports say two of the attackers were arrested by Egyptian security forces. In April, an Egyptian policeman and a civilian were killed in a similar incident in the Cairo neighborhood of Heliopolis. Egypt has been facing insecurity since the ouster of President Mohamed Morsi by the army on July 3. Militant groups have also stepped up their attacks on members of Egyptian security forces ever since. On Thursday, authorities in Egypt grounded several metro lines in Cairo after finding unexploded bombs on the tracks in a station. Egyptian security officials in the capital said on Thursday that bomb experts were sent to Helmeyet el-Zaytoun station in northeast Cairo to search the tracks for more possible explosive devices. Moreover, the surge in violence prompted Cairo to launch a major offensive against the militants and send thousands of troops backed by tanks and heavy equipment into the Sinai Peninsula.